小麦玉米轮作条件下不同生物质炭对土壤腐殖物质的影响

Effects of Application of Biochar on Soil Humic Substances in Cropland under Wheat-Corn Rotation System

生物质炭是有效的土壤固碳材料。通过1年的田间试验探究了小麦玉米轮作施用花生壳生物质炭和木材生物质炭后盐化潮土腐殖物质(HS)含量及化学结构的变化。试验设置不施肥(CK)、常规单施化肥(T1)、花生壳生物质炭(T2)、木材生物质炭(T3)4个处理。结果表明,与CK和T1处理相比,小麦季和玉米季生物质炭处理的土壤有机碳(soil organic carbon,SOC)含量均显著提高了。与小麦季相比,玉米季T2和T3处理胡敏素(humin,Hu)含量分别增加了0.54 g·kg^(–1)和0.35 g·kg^(–1)。在玉米季,T2和T3处理的土壤胡敏酸(humic acid,HA)、富里酸(fulvic acid,FA)和Hu在红外光谱(2 920+2 850)cm^(–1)处吸收峰相对强度均比小麦季升高了。与小麦季相比,玉米季T2处理HA和FA在1 630 cm^(–1)处吸收峰相对面积分别降低了2.46%和5.77%。与T3处理相比,玉米季T2处理Hu在1 630 cm^(–1)处吸收峰相对面积增加了0.33%;本试验中所用花生壳生物质炭芳香性物质相对含量较高。随着时间延长,T2处理土壤Hu的缩合度增加了,氧化度降低了,而T3处理则相反。生物质炭有利于提高土壤HS含量,尤其是Hu的含量。施用生物质炭后土壤Hu的缩合度增加了,氧化度降低了。生物质炭可增加HS亚甲基和甲基相对含量。不同材料来源生物质炭本身的化学结构差异性影响了土壤HS化学结构。

【Objective】Biochar is an effective soil carbon sequestrator.In this study,a one year field experiment was carried out to explore variation of content and chemical structure of the humic substances(HS)in salt stress fluvo-aquic soil under wheat-corn rotation.【Method】The experiment was designed to have four treatments,that is,CK(control,no fertilizer);T1((NH4)2HPO4 at 750 kg·hm^(-2));T2(peanut shell derived biochar 15 t·hm^(-2) plus(NH4)2·HPO4 at 750 kg·hm^(-2));T3(wood derived biochar 15 t·hm^(-2) plus(NH4)2HPO4 at 750 kg·hm^(-2)).【Result】Results show that biochar amendment increased the content of HS in the soil.Compared to the wheat growing season,the corn growing season had humin(Hu)increased in content by 0.54 g·kg^(-1) and 0.35 g·kg^(-1) in Treatments T2 and T3,respectively,and absorption peaks of the humic acid(HA),fulvic acid(FA)and Hu increased,too,in relative intensity at the 2920+2850 cm^(-1) band,while it had relative area of the absorption peaks of HA and FA at the 1630 cm^(-1) band decreased by 2.46%and 5.77%in Treatment T2.Compared to Treatment T3,Treatment T2 had relative area of the absorption peak of Hu at the 1630 cm^(–1) band increased by 0.33%in the corn growing season.The peanut shell derived biochar used in this experiment was relatively higher in content of aromatic groups than the wood derived biochar.Hu increased in condensation degree,while decreased in oxidation degree in Treatment T2,however,it acted reversely in Treatment T3.【Conclusion】Biochar was conducive to increasing of the content of HS,especially Hu,and it increased Hu in condensation degree and decreased Hu in oxidation degree with the experiment going on.Application of biochar could also increase relative contents of methylene and methyl in HS.The biochars derived from different materials are different in chemical structure,which in turn affects chemical composition of the HS in the soil.